1. Field of the Invention
The present invention relates to a method for forming inner flanges in a bushing which is used to secure a hose therein, where the bushing is used to attach the hose to exterior devices.
2. Description of Related Art
A conventional method for forming inner flanges in a bushing includes (a) providing an extruding die, (b) extruding a tubular bushing into the extruding die, (c) forming a first inner flange in the bushing and repeating steps (b) and (c) to form a desired number of distinct inner flanges in the bushing.
With reference to FIG. 14, the extruding die (20) comprises a first passage (21), a taper passage (22), and a second passage (23). The second passage (23) has a smaller diameter than the first passage (21) and the taper passage (22) reduces the diameter from that of the first passage (21) to that of the second passage (23). The bushing (40) has an inner periphery (not numbered), an outer periphery (not numbered), a leading end (not numbered) and a following end (not numbered). The leading end of the bushing (40) is extruded first in the extruding die (20), and the following end of the bushing (40) is extruded last in the extruding die (20). The punch (60) comprises a punch head (61) with an extension (611) that has a smaller diameter than the punch head (61).
With reference to FIG. 15, a stepped base (30) has four flat surfaces (301, 302, 303, 304) and a discharge hole (312). The extruding die (20) is perpendicular to the stepped base (30). The four flat surfaces (301, 302, 303, 304) comprise an uppermost flat surface (301), a second flat surface (302), a third flat surface (303) and a lowermost flat surface (304). The extruding die (20) with the bushing (40) and a pressing block (70) is slideably mounted on the stepped base (30) at the level of the uppermost flat surface (301).
With further reference to FIG. 16, the leading end of the bushing (40) is pressed into the first passage (21) of the extruding die (20) by the pressing block (70). The extension (611) of the punch head (61) extrudes the bushing (40) into the second passage (23). Therefore, the leading edge of the bushing (40) gradually decreases in diameter as the bushing (40) is extruded through the taper passage (22) and into the second passage (23) of the extruding die (20), and a first inner flange (401) is created.
With reference to FIGS. 16 and 17, the punch head (61) with the extension (611) is removed from the bushing (40), and the extruding die (20) is placed on the second flat surface (302) of the stepped base (30). The pressing block (70) presses the following end of the bushing (40) and extrudes the bushing (40) into the extruding die (20) until the leading end of the bushing (40) abuts the second flat surface (302) of the stepped base (30). The pressing block (70) is removed.
With reference to FIG. 18, the punch head (61) punches the inner periphery of the bushing (40) at the taper passage (22) to form a second inner flange (402).
With reference to FIGS. 19 and 20, the steps are repeated by driving the bushing (40) to the third flat surface (303) and the lowermost flat surface (304) of the stepped base (30), to form a third inner flange (403) and a fourth inner flange, (404) in the bushing (40).
When the fourth inner flange is completed, the bushing (41) is driven through the extruding die (20) and the discharge hole (312) on the lowermost flat surface (304) and is ready for exterior application. With reference to FIG. 15, the extruding die (20) is positioned over the uppermost flat surface (301) to make multiple inner flanges in another bushing (40). A new bushing (40) with a pressing block (70) is driven into the extruding die (20) until the bushing (40) abuts the uppermost flat surface (301) of the stepped base (30).
With reference to FIGS. 20 and 21, when the busing (41) is used to connect a hose (43), the disadvantage of the conventional method is that a weak connection is formed between the hose (43) and the bushing (41). When inner flanges (401, 402) are formed in the bushing (40) with the conventional method, the shape of each flange (401, 402) is rapidly caused by only one action of the punch head (61). Rapid movement of the punch head (61) will not act a uniform stress on the inner periphery of the bushing (40) during forming each inner flange (401, 402) so that the shape of each flange (40, 402, 402) will be not uniform and will be small. The shape of each flange (401, 402, 402) in bushing (40) results in the flanges (401, 402, 403) being weak and in small mounting area between adjacent flanges (401, 402, 402), and the small mounting area between adjacent flanges (401, 402, 402) causes the weak connection between the outer surface of the hose (43) and the bushing (41). Furthermore, the shape of each flange results in the deformation of flanges under a short period of lifetime.
To overcome the shortcomings, the present invention provides a method to form more effective flanges in a bushing to mitigate or obviate the aforementioned problems.
The primary objective of the present invention is to provide a method of forming improved inner flanges so that the bushing will provide a robust connection for a hose.
The method uses a flange punch to cut and form initial upward flanges in a bushing, and a flat head punch to flatten the initial upward flanges to final inner flanges. The two step method reduces punching impacts on the final inner flanges and strengthens the final inner flanges so that the bushing will provide a robust connection for connecting a hose.
Other objectives, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.